Electronic edition ISSN 1574-0579

The orientational relaxation and acoustical parameters of smectic "C" in a rotating magnetic field

S. V. Pasechnik

Abstract
The problem of reorientation of a smectic "C" liquid crystal with insignificantly distorted layer structure in a rotating magnetic field has been considered. It has been shown that in the case of an ideal monodomain of the smectic "C", there are synchronous and asynchronous regimes of motion of the director of quasinematic type. If there are any distortions of the layer structure of the smectic, then the synchronous regime vanishes, in principle, at any rotation velocity of the magnetic field. The problem of possible observation of the above peculiarities of the dynamical behaviour of the smectic "C" by measuring acoustical parameters in a rotating magnetic field has been discussed. An expression of the time dependence of ultrasound attenuation coefficient which could be verified experimentally has been derived. Fig. I, refs 9.